This invention relates to a method of making tapered tubes and more particularly to an improved method for making tapered tubes for uses such as utility poles.
As noted in the aforementioned application of Oliver C. Fuller, Ser. No. 481,679, the fabrication of hollow tapered tubes has provided several problems. The previously proposed methods have involved forming the tubes from sections made up from flat sheets which must, then, be curved into an arcuate shape. In addition to requiring additional metal forming steps, these methods of the prior art have resulted in some material wastage. As a result, tubes made from the prior art fabrication techniques have been relatively expensive thus limiting their application.
In accordance with the method disclosed in the earlier noted application, a tapered tube is formed from a cylindrical tube. The cylindrical tube is severed along a plane that is not parallel to the longitudinal axis of the tube and the resulting halves are then reversed one relative to the other for reassembly. The reassembled tube is deformed so that cross-sections will be circular in shape with circumferences that are equal to the lengths of the sums of the sides of the respective, reversed halves. As a result, the radius at the big end of the tube will be larger than the radius of the cylindrical tube from which the pole has been formed. The radius at the opposite end will depend upon the angle at which the cylindrical tube has been cut. Such an arrangement and method results in no wastage of material and elminates major forming steps that were required with the prior art methods to form the tubes out of flat stock. It is, however, necessary to reform the halves into a different radius from that of which the cylindrical tube had.
It is, therefore, a principal object of this invention to provide an improved and simplified method for manufacturing tapered tubes.
It is another object of this invention to provide an improved simplified method of forming tapered tubes from cylindrical tubes and for reforming the tapered sections into the desired radius.
It is yet a further object of this invention to provide an improved method for reforming a cylindrical segment into a segment having a tapered configuration of varying radius from one end to the other.